Etching solution for multilayer thin film having copper layer and molybdenum layer contained therein

ABSTRACT

Discloses are an etching solution for a multilayer thin film having a copper layer and a molybdenum layer contained therein; and an etching method of a multilayer thin film having a copper layer and a molybdenum layer contained therein using the same. Specifically disclosed are an etching solution for a multilayer thin film having a copper layer and a molybdenum layer contained therein, which includes (A) hydrogen peroxide, (B) a fluorine atom-free inorganic acid, (C) an organic acid, (D) an amine compound having a carbon number of from 2 to 10 and having an amino group and a hydroxyl group in a total group number of 2 or more, (E) an azole, and (F) a hydrogen peroxide stabilizer, and which has a pH of from 2.5 to 5; and an etching method using the same.

TECHNICAL FIELD

The present invention relates to an etching solution for a multilayerthin film having a copper layer and a molybdenum layer containedtherein. In particular, the etching solution of the present invention isfavorably used for etching a multilayer thin film having a copper layeris provided on a molybdenum layer.

BACKGROUND ART

Heretofore, aluminium or an aluminium alloy has been generally used asthe wiring material for display devices such as flat panel displays,etc. However, with growing in size and increasing in resolution ofdisplays, there has occurred a problem of RC delay caused by thecharacteristics such as the wiring resistance of such aluminium-basedwiring materials and uniform panel displaying has tended to bedifficult.

Given the situation, the recent tendency is toward investigation ofemploying copper or copper-based wiring with a material having a lowerresistance. However, copper has an advantage in that its resistance islow but, on the other hand, has a problem in that, in use for gatewiring, the adhesiveness between the substrate such as glass or the likeand copper is not sufficient and that, in use for source/drain wiring,copper may diffuse into the silicon semiconductor underlayer.Consequently, for preventing these, there has been made an investigationof barrier layer lamination with a metal that has high adhesion to asubstrate such as glass, etc. and hardly diffuses into the siliconsemiconductor underlayer and additionally has a barrier property; and asthe metal, molybdenum (Mo) has become specifically noted.

A multilayer film that contains copper or a copper-based copper alloy isformed on a substrate of glass or the like according to a film formationprocess of a sputtering method or the like, and then processed in anetching process of etching it via a resist serving as a mask to give anelectrode pattern. The etching process includes a wet etching mode ofusing an etching solution and a dry etching mode of using an etching gasof plasma or the like. The etching solution for use in the wet mode isdesired to satisfy the following: (i) The processing accuracy is high,(ii) the amount of the etching residue is small, (iii) the etchingunevenness level is low, and (iv) an etching performance is stableagainst dissolution of a metal of a wiring material containing copperwhich is subjective to etching (a prolonging effect of bath life); andin addition to these, for meeting the size enlargement and theresolution enhancement of displays, (v) the wiring configuration formedafter etching could fall within a predetermined range, or that is, agood wiring configuration can be obtained. More concretely, theparameters shown in FIG. 1 are desired to be as follows: The angle(taper angle) between the etched face of the copper wiring edge and thesubstrate is from 30 to 60°, or that is, the angle is a regular taperangle; the distance between the resist edge and the wire edge to be incontact with the barrier layer provided below the wire (CD loss) is notmore than 1.2 μm, and preferably not more than 1 μm.

As the etching solution to be used in the etching process for themultilayer film containing copper or a copper-based copper alloy, forexample, there have been proposed an etching solution containing atleast one selected from a neutral salt, an inorganic acid and an organicacid, and hydrogen peroxide and a hydrogen peroxide stabilizer (forexample, Patent Reference 1), an etching solution containing hydrogenperoxide, an organic acid and fluorine (for example, Patent Reference2), etc.

However, these are all unsatisfactory in point of the wiring profileafter etching therewith and, as a result, could not often sufficientlymeet the size enlargement and the resolution enhancement of displays.Also, the etching solution disclosed in Patent Reference 2 contains afluorinated compound, so that it was not thoroughly satisfactory fromthe viewpoint of environmental measure.

PRIOR ART DOCUMENTS Patent Documents

-   Patent Reference 1: Japanese Patent No. 4282927-   Patent Reference 2: JP-A-2004-193620

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 This is a schematic view of a wiring cross section that has amultilayer thin film containing a copper layer and a molybdenum layer,as etched with the etching solution of the present invention.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

The present invention has been made under the circumstances as above,and its object is to provide an etching solution for a multilayer thinfilm containing a copper layer and a molybdenum layer, and a method ofusing it for etching a multilayer thin film containing a copper layerand a molybdenum layer.

Means for Solving the Problems

The present inventors have repeatedly made assiduous studies forattaining the above-mentioned object. As a result, it has been foundthat the foregoing object can be achieved by an etching solutionobtained by blending (A) hydrogen peroxide, (B) a fluorine atom-freeinorganic acid, (C) an organic acid, (D) an amine compound, (E) anazole, and (F) a hydrogen peroxide stabilizer in a specified combinationand regulating its pH within the range of from 2.5 to 5.

The present invention has been completed on the basis of the finding.Specifically, the gist of the present is as follows:

[1] An etching solution for a multilayer thin film having a copper layerand a molybdenum layer contained therein, which comprises (A) hydrogenperoxide, (B) a fluorine atom-free inorganic acid, (C) an organic acid,(D) an amine compound having a carbon number of from 2 to 10 and havingan amino group and a hydroxyl group in a total group number of 2 ormore, (E) an azole, and (F) a hydrogen peroxide stabilizer, and whichhas a pH of from 2.5 to 5.[2] The etching solution as set forth above in [1], wherein theinorganic acid (B) is sulfuric acid and/or nitric acid.[3] The etching solution as set forth above in [1] or [2], wherein theorganic acid (C) is at least one member selected among succinic acid,glycolic acid, lactic acid, malonic acid, and malic acid.[4] The etching solution as set forth above in any one of [1] to [3],wherein the amine compound (D) is at least one member selected amongethanolamine, 1-amino-2-propanol, and N,N-diethyl-1,3-propanediamine.[5] The etching solution as set forth above in any one of [1] to [4],wherein the azole (E) is 5-amino-1H-tetrazole.[6] The etching solution as set forth above in any one of [1] to [5],wherein the hydrogen peroxide stabilizer (F) is phenylurea.[7] The etching solution as set forth above in any one of [1] to [6],comprising from 4.5 to 7.5% by mass of the hydrogen peroxide (A), from0.01 to 3% by mass of the inorganic acid (B), from 5 to 13% by mass ofthe organic acid (C), from 2 to 7% by mass of the amine compound (D),from 0.001 to 0.5% by mass of the azole (E), and from 0.01 to 0.5% bymass of the hydrogen peroxide stabilizer (F).[8] The etching solution as set forth above in any one of [1] to [7],further comprising 200 ppm or more of a copper ion.[9] The etching solution as set forth above in any one of [1] to [8],wherein the multilayer thin film is one having a copper layer laminatedon a molybdenum layer.[10] A method for etching a multilayer thin film containing a copperlayer and a molybdenum layer, which comprises bringing a subject to beetched into contact with the etching solution of any of the above [1] to[8].[11] The etching method of the above [10], wherein the multilayer thinfilm is one formed by laminating a copper layer on a molybdenum layer.

Effects of the Invention

According to the present invention, there are provided an etchingsolution which secures, in an etching process for a multilayer thin filmcontaining a copper layer and a molybdenum layer, high processingaccuracy, little etching residue and unevenness and a long bath life,and realizes a good wiring profile after etching therewith, and whichtherefore can meet the requirement of size enlargement and resolutionenhancement of displays, and an etching method using it for a multilayerthin film containing a copper layer and a molybdenum layer. According tothe etching method, a wiring material that contains a multilayer thinfilm containing a copper layer and a molybdenum layer can be etched allat a time, and therefore, after etching therewith, a good wiring profilecan be realized at high producibility.

BEST MODES FOR CARRYING OUT THE INVENTION [Etching Solution forMultilayer Thin Film Having Copper Layer and Molybdenum Layer ContainedTherein]

The etching solution of the present invention is used for etching of amultilayer thin film having a copper layer and a molybdenum layercontained therein, and it comprises (A) hydrogen peroxide, (B) afluorine atom-free inorganic acid, (C) an organic acid, (D) an aminecompound having a carbon number of from 2 to 10 and having an aminogroup and a hydroxyl group in a total group number of 2 or more, (E) anazole, and (F) a hydrogen peroxide stabilizer, and has a pH of from 2.5to 5.

<<(A) Hydrogen peroxide>>

Hydrogen peroxide which is used in the etching solution of the presentinvention has a function to oxidize a copper wiring as an oxidizingagent and also has a function to oxidize and dissolve molybdenum. Acontent of hydrogen peroxide in the etching solution is preferably from3 to 10% by mass, and more preferably from 4.5 to 7.5% by mass. Thecontent of hydrogen peroxide falling within the above range ispreferred, the control of hydrogen peroxide is easy, and also assecuring a suitable etching rate and facilitating good control of theetching amount. Thus, such is preferable.

<<(B) Fluorine Atom-Free Inorganic Acid>>

The fluorine atom-free inorganic acid which is used in the etchingsolution of the present invention contributes to the dissolution ofcopper which has been oxidized with the hydrogen peroxide (A). In thepresent invention, from the viewpoint of environmental measure, afluorine atom-free acid is adopted. As the fluorine atom-free inorganicacid, sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid,hypophosphorous acid, carbonic acid, sulfamic acid, boric acid, and thelike are preferably exemplified. These can be used alone or in admixtureof a plurality thereof. Above all, sulfuric acid and nitric acid arepreferable.

A content of the inorganic acid (B) in the etching solution ispreferably from 0.01 to 5% by mass, and more preferably from 0.01 to 3%by mass. When the content of the inorganic acid falls within the aboverange, a suitable etching rate can be secured and a good wiring profilecan be obtained after etching.

<<(C) Organic Acid>>

The organic acid which is used in the etching solution of the presentinvention contributes to the etching of copper and molybdenum and theremoval of a residue to be caused due to molybdenum, and the contentthereof in the etching solution is preferably from 1 to 15% by mass,more preferably from 5 to 13% by mass. When the content of the organicacid falls within the above range, etching of copper and molybdenum andthe removal of a residue to be caused due to molybdenum can besufficiently achieved, and also, a good wiring profile can be obtainedafter etching. Also, the organic acid functions as a masking agent of acopper ion to be contained in the etching solution after etching and isable to inhibit the decomposition of hydrogen peroxide with copper.

As the organic acid, in addition to aliphatic carboxylic acids having acarbon number of from 1 to 18 and aromatic carboxylic acids having acarbon number of from 6 to 10, amino acids having a carbon number offrom 1 to 10 and the like are preferably exemplified.

As the aliphatic carboxylic acid having a carbon number of from 1 to 18,formic acid, acetic acid, propionic acid, lactic acid, glycolic acid,diglycolic acid, pyruvic acid, malonic acid, butyric acid,hydroxybutyric acid, tartaric acid, succinic acid, malic acid, maleicacid, fumaric acid, valeric acid, glutaric acid, itaconic acid, adipicacid, caproic acid, adipic acid, citric acid, propanetricarboxylic acid,trans-aconitic acid, enanthic acid, caprylic acid, lauric acid, myristicacid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenicacid, and the like are preferably exemplified.

As the aromatic carboxylic acid having a carbon number of from 6 to 10,benzoic acid, salicylic acid, mandelic acid, phthalic acid, isophthalicacid, terephthalic acid, and the like are preferably exemplified.

Also, as the amino acid having a carbon number of from 1 to 10, carbamicacid, alanine, glycine, asparagine, aspartic acid, sarcosine, serine,glutamine, glutamic acid, 4-aminobutyric acid, iminodibutyric acid,arginine, leucine, isoleucine, nitrilotriacetic acid, and the like arepreferably exemplified.

Of the foregoing organic acids, acetic acid, succinic acid, alanine,citric acid, malic acid, lactic acid, glycolic acid, tartaric acid,malonic acid, glycine, glutaric acid, maleic acid, and trans-aconiticacid are preferable as the organic acid, with succinic acid, malic acid,lactic acid, glycolic acid, and malonic acid being especiallypreferable. These can be used alone or in combination of a pluralitythereof.

<<(D) Amine Compound>>

The amine compound which is used in the etching solution of the presentinvention contributes to the favorable wiring profile after etching andis a compound having a carbon number of from 2 to 10 and having an aminogroup and a hydroxyl group in a total group number of 2 or more.

As such an amine compound, polyamines such as ethylenediamine,trimethylenediamine, tetramethylenediamine, 1,2-propanediamine,1,3-propanediamine, N,N-dimethyl-1,3-propanediamine,N,N-diethyl-1,3-propanediamine, 1,3-diaminobutane, 2,3-diaminobutane,pentamethylenediamine, 2,4-diaminopentane, hexamethylenediamine,heptamethylenediamine, octamethylenediamine, nonamethylenediamine,N-methylethylenediamine, N,N-dimethylethylenediamine,trimethylethylenediamine, N-ethylethylenediamine,N,N-diethylethylenediamine, triethylethylenediamine,1,2,3-triaminopropane, hydrazine, tris(2-aminoethyl)amine,tetra(aminomethyl)methane, diethylenetriamine, triethylenetetramine,tetraethylpentamine, heptaethyleneoctamine, nonaethylenedecamine,diazabicycloundecene, etc.; and alkanolamines such as ethanolamine,N-methylethanolamine, N-methyl diethanolamine, N-ethylethanolamine,N-aminoethylethanolamine, N-propylethanolamine, N-butylethanolamine,diethanolamine, triethanolamine, 1-amino-2-propanol,N-methylisopropanolamine, N-ethylisopropanolamine,N-propylisopropanolamine, 2-aminopropane-1-ol,N-methyl-2-amino-propane-1-ol, N-ethyl-2-amino-propane-1-ol,1-aminopropane-3-ol, N-methyl-1-aminopropane-3-ol,N-ethyl-1-aminopropane-3-ol, 1-aminobutane-2-ol,N-methyl-1-aminobutane-2-ol, N-ethyl-1-aminobutane-2-ol,2-aminobutane-1-ol, N-methyl-2-aminobutane-1-ol,N-ethyl-2-aminobutane-1-ol, 3-aminobutane-1-ol,N-methyl-3-aminobutane-1-ol, N-ethyl-3-aminobutane-1-ol,1-aminobutane-4-ol, N-methyl-1-aminobutane-4-ol,N-ethyl-1-aminobutane-4-ol, 1-amino-2-methylpropane-2-ol,2-amino-2-methylpropane-1-ol, 1-aminopentane-4-ol,2-amino-4-methylpentane-1-ol, 2-aminohexane-1-ol, 3-aminoheptane-4-ol,1-aminooctane-2-ol, 5-aminooctane-4-ol, 1-aminopropane-2,3-diol,2-aminopropane-1,3-diol, tris(oxymethyl)aminomethane,1,2-diaminopropane-3-ol, 1,3-diaminopropane-2-ol,2-(2-aminoethoxy)ethanol, 2-(2-aminoethylamino)ethanol, diglycolamine,etc. are preferably exemplified. These can be used alone or incombination of a plurality thereof. Of these, ethanolamine,1-amino-2-propanol, and N,N-diethyl-1,3-propanediamine are especiallypreferable.

A content of the amine compound in the etching solution of the presentinvention is preferably from 1 to 10% by mass, and more preferably from2 to 7% by mass. When the content of the amine compound falls within theabove range, a good wiring profile can be obtained after etching.

<<(E) Azole>>

As the azole which is used in the etching solution of the presentinvention, triazoles such as 1H-benzotriazole,5-methyl-1H-benzotriazole, 3-amino-1E-triazole, etc.; tetrazoles such as1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole,5-amino-1H-tetrazole, etc.; imidazoles such as 1H-imidazole,1H-benzoimidazole, etc.; thiazoles such as 1,3-thiazole,4-methylthiazole, etc.; and the like are preferably exemplified. Ofthese, tetrazoles are preferable, and 5-amino-1H-tetrazole is especiallypreferable.

The content of the azole in the etching solution is preferably from0.001 to 1% by mass, more preferably from 0.001 to 0.5% by mass. Whenthe content of the azole falls within the above range, a good wiringprofile can be obtained while suppressing an increase of CD loss afteretching.

<<(F) Hydrogen Peroxide Stabilizer>>

The etching solution of the present invention contains a hydrogenperoxide stabilizer. Not specifically defined, any one generally used asa hydrogen peroxide stabilizer is usable here with no limitation;however, as the hydrogen peroxide stabilizer for use herein, preferablymentioned are urea-based hydrogen peroxide stabilizers such asphenylurea, allylurea, 1,3-dimethylurea, thiourea, etc., as well asphenylacetamide, phenylethylene glycol, etc. Above all, preferred isphenylurea.

The content of the hydrogen peroxide stabilizer (F) in the etchingsolution of the present invention is preferably from 0.01 to 0.5% bymass, more preferably from 0.01 to 0.3% by mass from the viewpoint ofsufficiently securing the addition effect thereof.

<<pH>>

The etching solution of the present invention is required to have a pHof 2.5 to 5. When its pH is less than 2.5, a residue derived from amolybdenum oxide, which is hardly dissolved, which is formed at the timewhen molybdenum is etched and dissolved, is remained after etching, andas a result, there is a concern that the residue can bring on a loweringof electrical characteristics caused by leak current. Also, when the pHis larger than 5, then the stability of the hydrogen peroxide (A) maylower whereby the etching rate for copper wiring may lower and the bathlife of the etching solution may shorten. From such viewpoints, the pHof the etching solution of the present invention is preferably from 2.5to 5.

<<Copper Ion>>

For the purpose of enhancing an etching performance from the beginningof use, it is preferable to allow the etching solution of the presentinvention to contain a copper ion in advance. The copper ion can becontained in the etching solution by adding a copper powder or a coppersalt such as copper sulfate, copper nitrate, etc. to the etchingsolution.

A concentration of the copper ion in the etching solution is preferably100 ppm or more, and more preferably 200 ppm or more. Also, though anupper limit of the concentration is not restricted so far as the etchingperformance is not lowered, taking into consideration a bath life andthe like, it is preferably not more than 2,000 ppm, and more preferablynot more than 1,000 ppm.

<<Other Components>>

The etching solution of the present invention may contain, in additionto the foregoing components (A) to (F), water and other variousadditives which are usually used in etching solutions, within the rangewhere the effects of the etching solution are not impaired. The water ispreferably one from which metal ions or organic impurities, particles,and the like have been removed by means of distillation, ion exchangetreatment, filter treatment, adsorption treatment of every kind, or thelike, and pure water and ultra-pure water are especially preferable.

[Etching Method of Multilayer Thin Film Having Copper Layer andMolybdenum Layer Contained Therein]

The etching method of the present invention is a method for etching amultilayer thin film that contains a copper layer and a molybdenumlayer, and is characterized in that the etching solution of the presentinvention, or that is, the etching solution for a multilayer thin filmcontaining a copper layer and a molybdenum layer, which comprises (A)hydrogen peroxide, (B) a fluorine atom-free inorganic acid, (C) anorganic acid, (D) an amine compound having a carbon number of from 2 to10 and having an amino group and a hydroxyl group in a total groupnumber of 2 or more, (E) an azole, and (F) a hydrogen peroxidestabilizer, and which has a pH of from 2.5 to 5 is used and that themethod comprises a step of bringing a subject to be etched into contactwith the etching solution of the present invention. According to theetching method of the present invention, a multilayer thin filmcontaining a copper layer and a molybdenum layer can be etched all at atime to give a good wiring profile after etching.

In the etching method of the present invention, the subject to be etchedwith the etching solution is one, for example, as shown in FIG. 1, inwhich a barrier film (molybdenum layer) formed of a molybdenum-basedmaterial and a copper wire (copper layer) formed of copper or acopper-based material are laminated in that order on a substrate ofglass or the like to form a multilayer thin film containing the copperlayer and the molybdenum layer, a resist is further applied thereonto,and a desired pattern mask is transferred on it through exposure anddevelopment to form a desired resist pattern thereon. In the presentinvention, the multilayer thin film containing a copper layer and amolybdenum layer includes an embodiment where the copper layer exists onthe molybdenum layer as in FIG. 1, and also an embodiment where themolybdenum layer exists on the copper layer. The multilayer thin film ofthe type containing a copper layer and a molybdenum layer is favorablyused in wiring in display devices such as flat panel displays, etc.Consequently, the subject to be etched in which a copper layer exists ona molybdenum layer is a favorable embodiment from the viewpoint of theindustrial applicability thereof.

Not specifically defined, the copper wiring may be formed of copper or acopper-based material, and as the molybdenum-based material to form thebarrier film, there may be mentioned molybdenum (Mo) metal, an Mo basedalloy, and so on.

The method of bringing the subject to be etched into the etchingsolution is not specifically defined; and herein employable is a wetetching method, for example, a method of dripping the etching solutiononto the subject (sheet-fed spin treatment) or spraying it thereonto, ora method of dipping the subject into the etching solution, etc. In thepresent invention, preferably employed is the method of dripping theetching solution onto the subject (sheet-fed spin treatment) or sprayingit thereonto, or the method of dipping the subject into the etchingsolution.

The temperature at which the etching solution is used is preferably from20 to 60° C., more preferably from 30 to 50° C. When the temperature ofthe etching solution is not lower than 20° C., then the etching rate isnot so much lowered and the production efficiency is not extremelylowered. On the other hand, when the temperature is not higher than aboiling point, then the solution composition change could be preventedand the etching condition could be kept constant. Elevating thetemperature of the etching solution could increase the etching rate, butin consideration of the object of reducing the composition change of theetching solution, the best treatment temperature may be suitablydetermined.

In the etching method of the present invention, the hydrogen peroxide(A) contained in the etching solution is consumed by oxidation anddissolution of copper or molybdenum as described above, or the like, andthe dissolved copper or molybdenum accelerates the decomposition ofhydrogen peroxide. Therefore, there is a concern that a lowering of theperformance of the etching solution to be caused due to a lowering ofthe hydrogen peroxide concentration. In such a case, hydrogen peroxide(A) and the organic acid (B) may be simultaneously or separately addedso as to prolong the bath life of the etching solution.

EXAMPLES

Next, the present invention is described in more detail by reference tothe following Examples, but it should be construed that the presentinvention is not limited by these Examples at all.

(Observation of Cross Section of Multilayer Thin Film Having CopperLayer and Molybdenum Layer Contained Therein after Etching)

A sample of the etched multilayer thin film containing a copper layerand a molybdenum layer, as obtained in Examples and ComparativeExamples, was cut and observed with a 30000 magnification throughscanning electronic microscope (“S5000H

Type (Model Number)”, by Hitachi) (acceleration voltage 2 kV,acceleration current 10 μA). On the thus-taken SEM image, the taperangle and the CD loss (μm) as shown in FIG. 1 were determined.

When the taper angle and the CD loss (μm) fell within the standardranges shown in Table 1, the sample was considered to be acceptable forthe etching performance.

(Evaluation of Etching Residue)

A surface of a multilayer thin film sample having a copper layer and amolybdenum layer contained thereon after etching, as obtained in each ofthe Examples and Comparative Examples, was observed using a scanningelectron microscope (S5000 Model (model number), manufactured byHitachi, Ltd.) in an observation magnification of 50,000 times(accelerating voltage: 2 kV, accelerating current: 10 μA), and a residueof the sample was evaluated according to the following criteria.

A: A residue was not confirmed at all.

B: Though a residue was slightly confirmed, the wiring performance wasnot influenced, so that no problem was caused from the standpoint ofpractical use.

C: A remarkable residue was confirmed.

TABLE 1 Acceptable range CD loss (= a) (μm) Not more than 1 Taper angle(°) 30 to 60

Fabrication Example Fabrication of Multilayer Thin Film Having CopperLayer and Molybdenum Layer Contained Therein

Molybdenum (Mo) was sputtered onto a substrate of glass to thereby forma barrier film of molybdenum (molybdenum layer) thereon, then acopper-based material was sputtered thereonto to form a wiring materialfilm (copper layer), then a resist was applied onto it, a pattern maskwas transferred through exposure thereonto, and developed to form awiring pattern, thereby fabricating a multilayer thin film containing acopper layer and a molybdenum layer in which the copper layer waslaminated on the molybdenum layer.

Examples 1 to 5

The multilayer thin film having a copper layer and a molybdenum layer asobtained in the Fabrication Example was repeatedly subjected to anoperation of etching with an etching solution shown in Table 2 at 35° C.by means of shower spraying; and with respect to the obtained multilayerthin film having a copper layer and a molybdenum layer after etching, ataper angle and a CD loss (μm) were obtained in a low-concentrationregion of a copper ion concentration in the etching solution (alsoexpressed as “Cu concentration”) (from 200 to 1,000 ppm; also expressedas “low Cu concentration region”) and a high-concentration region of acopper ion concentration in the etching solution (from 3,000 to 4,000ppm; also expressed as “high Cu concentration region”) by means of SEMobservation.

Also, a time at which an etching subject of an area where the resist hadnot been patterned was determined to be etched by means of visualinspection was set up as a just etching time; and a time at which anetching treatment (overetching) was performed in an arbitrary proportionwithin the range of from 110 to 300% of the just etching time was set upas an etching time (for example, when the just etching time is 100seconds, so far as overetching of 50% is concerned, its etching time is150 seconds). These results of evaluations are shown in Table 2.

TABLE 2 Example 1 2 3 4 5 Etching Solution 1 2 3 4 5 (A) Hydrogenperoxide*¹ (% by 5.8 5.8 5.8 5.8 4.5 mass) (B) Nitric acid*² (% by 0.070.07 0.07 1.63 0.05 mass) (C) Succinic acid*² (% by 3.0 3.0 3.0 3.0 3.0mass) Glycolic acid*² (% by 2.0 2.0 2.0 2.0 2.0 mass) Lactic acid*² (%by 1.0 1.0 — 1.0 1.0 mass) Malonic acid*² (% by 2.0 3.0 3.5 0.5 2.0mass) Malic acid*² (% by 2.0 — — — 2.0 mass) (D) Ethanolamine*² (% by —— — — — mass) 1-Amino-2-propanol*² (% by — 2.8 2.8 — — mass)N,N-Diethyl-1,3-propanediamine*² (% by 4.0 — — 4.9 5.5 mass) (E) Azole*³(% by 0.05 0.05 0.1 0.003 0.025 mass) (F) Hydrogen peroxide stabilizer*⁴(% by 0.1 0.1 0.1 0.1 0.1 mass) Water (% by Balance Balance BalanceBalance Balance mass) pH 3.5 3.0 3.0 3.9 4.0 Cu film thickness/Mo filmthickness angstrom/ 3000/300  3000/300  3000/300  5000/200  3000/300 angstrom Cu concentration at the time of evaluation ppm 1000/40001000/4000 1000/4000 1000/4000  500/3000 (low-concentrationregion/high-concentration region) Just etching time (low Cuconcentration sec 83/65 63/61 62/70 82/86 98/85 region/high Cuconcentration region) Etching time sec 126 110 110 120 147 Taper angle(low Cu concentration region/high degree 35/50 30/40 30/40 40/30 35/50Cu concentration region) CD loss (low Cu concentration region/high Cu μm0.75/0.79  1.0/0.84 0.82/0.64 0.92/0.92 0.82/0.74 concentration region)Overall evaluation of wiring cross-sectional shape A A A A A Evaluationof residue (low Cu concentration region/high Cu A/A A/A A/A A/A A/Aconcentration region) *¹Manufactured by Mitsubishi Gas Chemical Company,Inc. *²Manufactured by Wako Pure Chemical Industries, Ltd.*³5-Amino-1H-tetrazole, manufactured by Wako Pure Chemical Industries,Ltd. *⁴Phenylurea, manufactured by Wako Pure Chemical Industries, Ltd.

Examples 6 and 7

As Examples 6 and 7, etching was performed in the same manner as that inExample 4, except that in Example 4, a copper powder was previouslyadded in a copper ion concentration of 200 ppm and 6,000 ppm,respectively to the Etching Solution 4 to be used. A taper angle, a CDloss (μm), and evaluation of residue of the multilayer thin film havinga copper layer and a molybdenum layer contained therein, as obtained inthe first etching are shown in Table 3. Also, a taper angle, a CD loss(μm), and evaluation of residue of the multilayer thin film having acopper layer and a molybdenum layer of Example 4 as obtained in thefirst etching are shown in Table 3.

TABLE 3 Example 4 (First etching) 6 7 Copper ion concentration ppm 0 2006000 Cu film thickness/Mo angstrom/ 5000/200 5000/200 5000/200 filmthickness angstrom Just etching time sec 80 80 101 Etching time sec 120120 120 Taper angle degree 35 40 30 CD loss μm 1.0 1.0 0.65 Overallevaluation of wiring cross- A A A sectional shape Evaluation of residueB A A Evaluation of crystal deposition A A A

Comparative Examples 1 to 5

Samples were etched in the same manner as in Example 1, except that theetching solution comprising the components shown in Table 4 was used inExample 1. A taper angle, a CD loss (μm), and evaluation of residue ofeach of the obtained multilayer thin films having a copper layer and amolybdenum layer are shown in Table 4.

TABLE 4 Comparative Example 1 2 3 4 5 Etching Solution 6 7 8 9 10 (A)Hydrogen peroxide*¹ (% by 5.8 6.0 6.0 5.8 5.8 mass) (B) Nitric acid*² (%by — — — 0.07 0.07 mass) (C) Succinic acid*² (% by 3.0 — — 3.0 3.0 mass)Glycolic acid*² (% by 2.0 — — 2.0 2.0 mass) Lactic acid*² (% by — — —1.0 1.0 mass) Malonic acid*² (% by 2.0 — — 3.0 3.0 mass) Malic acid*² (%by 2.0 — — — — mass) (D) N,N-Diethyl-1,3-propanediamine*² (% by 3.6 — —— — mass) 1-Amino-2-propanal*² (% by — — — 2.8 — mass) (E) Azole*³ (% by0.05 — — 0.05 0.05 mass) (F) Hydrogen peroxide stabilizer*⁴ (% by 0.1 —— 0.1 0.1 mass) Ammonia (% by — — — — 1.0 mass) Sodium chloride (% by —5.0 — — — mass) Potassium hydrogensulfate (% by — — 5.0 — — mass) Water(% by Balance Balance Balance Balance Balance mass) pH 3.5 4.9 0.9 1.53.5 Cu film thickness/Mo film thickness angstrom/ 3000/300  3000/3003000/300 3000/300  3000/300  angstrom Cu concentration at the time ofevaluation ppm  500/4000 0 0 1000/4000 1000/4000 (low-concentrationregion/high-concentration region) Just etching time (low Cuconcentration sec 84/83 180 sec or 98 52/55 51/63 region/high Cuconcentration region) more Etching time sec 126 — 150 130 130 Taperangle (low Cu concentration region/high degree 35/40 — — 25/28 ReverselyCu concentration region) tapered CD loss (low Cu concentrationregion/high Cu μm 0.64/0.60 — — 1.72/1.18 1.57/1.0  concentrationregion) Overall evaluation of wiring cross-sectional shape C*⁵ C*⁶ C*⁷ CC Evaluation of residue (low Cu concentration region/high Cu B/A — — B/AA/A concentration region) *⁵In the high Cu concentration region, in thewiring cross-sectional shape, undercut in which molybdenum as the lowerlayer was more selectively etched than copper as the upper layer wasgenerated. *⁶The etching was not achieved. *⁷The resist was peeled.

The Examples using the etching solution of the present invention werefavorable in the wiring cross-sectional shape after etching and alsoexhibited excellent results in view of the evaluation of residue. On theother hand, in Comparative Example 1 using an etching solution notcontaining the component (B), in the wiring cross-sectional shape,so-called undercut in which molybdenum as the lower layer was moreselectively etched than copper as the upper layer was generated. InComparative Examples 2 and 3 using an etching solution not containingthe components (B) to (F), the etching did not proceed, or the resistwas peeled, so that it was confirmed that these etching solutions cannotbe put into practical use. Also, in Comparative Example 4 using anetching solution having a pH falling outside the range specified in theinvention of the present application, the CD loss was large; and inComparative Example 5 using an etching solution not containing thecomponent (D), molybdenum as the lower layer was selectively etched, andthe etched edge face was not formed in a forward tapered shape but areversely tapered shape in which the taper angle partially exceeded 90°,so that it was confirmed that a problem was caused from the standpointof wiring cross-sectional shape.

The wiring cross-sectional shape after first etching in Examples 6 and 7using an etching solution previously containing 200 ppm and 6,000 ppm ofa copper ion, respectively was favorable as compared with the wiringcross-sectional shape after first etching in Example 4, so that it wasconfirmed that the evaluation of residue was favorable. That is, it wasconfirmed that when a copper ion is previously added in the etchingsolution of the present invention, a favorable performance is revealedfrom the beginning of use of the etching solution.

INDUSTRIAL APPLICABILITY

The etching solution of the present invention can be favorably used foretching of a copper layer and a molybdenum layer contained therein; andaccording to the etching method of using the etching solution, amultilayer thin film containing a copper layer and a molybdenum layercan be etched all at a time to have a good wiring profile after etching,therefore realizing high producibility.

1. An etching solution, comprising: (A) hydrogen peroxide; (B) a fluorine atom-free inorganic acid; (C) an organic acid; (D) an amine compound comprising from 2 to 10 carbons and at least two selected from the group consisting of an amino group and a hydroxyl group; (E) an azole; and (F) a hydrogen peroxide stabilizer, wherein the etching solution has a pH of from 2.5 to
 5. 2. The etching solution of claim 1, wherein the inorganic acid (B) is sulfuric acid, nitric acid, or a mixture thereof.
 3. The etching solution of claim 1, wherein the organic acid (C) is succinic acid, glycolic acid, lactic acid, malonic acid, malic acid, or any mixture thereof.
 4. The etching solution of claim 1, wherein the amine compound (D) is ethanolamine, 1-amino-2-propanol, N,N-diethyl-1,3-propanediamine, or any mixture thereof.
 5. The etching solution of claim 1, wherein the azole (E) is 5-amino-1H-tetrazole.
 6. The etching solution of claim 1, wherein the hydrogen peroxide stabilizer (F) is phenylurea.
 7. The etching solution of claim 1, comprising: from 4.5 to 7.5% by mass of the hydrogen peroxide (A); from 0.01 to 3% by mass of the inorganic acid (B); from 5 to 13% by mass of the organic acid (C); from 2 to 7% by mass of the amine compound (D); from 0.001 to 0.3% by mass of the azole (E); and from 0.01 to 0.5% by mass of the hydrogen peroxide stabilizer (F).
 8. The etching solution of claim 1, further comprising: from 100 to 2000 ppm of a copper ion.
 9. The etching solution of claim 1, wherein the etching solution is adapted for a multilayer thin film comprising a copper layer and a molybdenum layer, wherein the copper layer is laminated on the molybdenum layer.
 10. A method for etching a multilayer thin film comprising a copper layer and a molybdenum layer, the method comprising: contacting an etching subject with the etching solution of claim
 1. 11. The method of claim 10, wherein the multilayer thin film comprises a copper layer laminated on a molybdenum layer.
 12. The etching solution of claim 7, wherein the inorganic acid (B) is sulfuric acid, nitric acid, or a mixture thereof.
 13. The etching solution of claim 7, wherein the organic acid (C) is succinic acid, glycolic acid, lactic acid, malonic acid, malic acid, or any mixture thereof.
 14. The etching solution of claim 7, wherein the amine compound (D) is ethanolamine, 1-amino-2-propanol, N,N-diethyl-1,3-propanediamine, or any mixture thereof.
 15. The etching solution of claim 7, wherein the azole (E) is 5-amino-1H-tetrazole.
 16. The etching solution of claim 7, wherein the hydrogen peroxide stabilizer (F) is phenylurea.
 17. The etching solution of claim 12, wherein the organic acid (C) is succinic acid, glycolic acid, lactic acid, malonic acid, malic acid, or any mixture thereof.
 18. The etching solution of claim 17, wherein the amine compound (D) is ethanolamine, 1-amino-2-propanol, N,N-diethyl-1,3-propanediamine, or any mixture thereof.
 19. The etching solution of claim 18, wherein the azole (E) is 5-amino-1H-tetrazole.
 20. The etching solution of claim 19, wherein the hydrogen peroxide stabilizer (F) is phenylurea. 